During an approach trajectory with a view to a landing (be it considered “non-precision”, that is to say with absence of joining of the runway threshold, or by visual approach or else by circling manoeuvre (MVL) or visual manoeuvring using prescribed track (VPT)), no aid is offered to the pilot to determine whether the aircraft will succeed in joining the runway threshold in a sufficiently stabilized manner to carry out the landing thereof.
In particular, no trajectory between the so-called “MAP” point (according to the beacon, VOR or DME) and the runway threshold point is available. The procedure is generally “flown by sight” from the MAP. Likewise for “non-precision” approaches which stop at the beacon and not at the runway threshold, the remainder of the procedure is flown by sight by the pilot.
Furthermore, for appropriate approach trajectories which lead to the runway threshold, when the air navigation provides its directives (“clearances”), these do not always correspond to the lateral and/or vertical parameters corresponding to the approach trajectory selected by the pilot. The latter must therefore judge the situation in an autonomous manner with respect to the trajectory provided by the FMS. For visual approaches, the approach trajectory is not generally optimized since it does not provide any joining of the so-called “Final Fix” point. For “precision” and “non-precision” approaches which lead to the runway threshold, for example in case of “radar vectoring” by the air navigation (e.g. the aircraft does not therefore fly the procedure as referenced in the navigation database), the pilot does not receive any aid with positioning the aircraft (notably in a vertical manner with respect to an optional ILS beam and with determining the moment at which he must carry out his turn so as to be placed correctly with respect to the runway threshold).
The current systems are generally characterized by an absence of possibility of constructing the approach manoeuvre (e.g. no storage: in the NAVDBs; difficulties for existing FMS flight management systems in respect of managing an arrival via a star/VIA on a runway, and in stringing this procedure together with a landing runway other than that related to the procedure)/
Moreover, the current solutions do not make it possible to calculate the energy dissipation over the trajectory which will actually be flown, thereby generally resulting in false alerts (i.e. too much energy for the landing, such alerts being unwarranted).
The prior art generally describes methods for calculating distance necessary to land on the runway (“Required Distance to Land” or RDTL) but this distance is generally determined by a direct distance to the runway and by the energy to be dissipated before reaching the runway. This approach comprises limitations. For example, patent document U.S. Pat. No. 6,438,469 entitled “FLIGHT CONTROL SYSTEM AND METHOD FOR AN AIRCRAFT CIRCLE-TO-LAND MANEUVER” describes a system for calculating a trajectory in the context of a visual approach. This approach also comprises limitations.
The present invention discloses several embodiments exhibiting advantages in relation to the limitations mentioned hereinabove.